DATA DETAILS

August 18, 2005 through November 17, 2006:

This tower is the sole 50m anemometer tower owned by the Governor's Energy Office. It is intended for community wind projects. Funding for the site came from San Isabel Electric
Association, Inc. and the Governor's Energy Office. The anemometer tower was installed in August 18, 2005. The original 20-meter tower at the West Walsenburg site was removed and replaced with this 50-meter tower. Because of more sensors and
measurement heights, the site was given a new name, West Walsenburg #2. The site was located approximately 10 miles northwest of the town of Walsenburg. Two miles to the north is the Huerfano River which is
oriented in a west-to-east direction. The vegetation around the site is primarily grassland and brush.

Data was collected using four (4) NRG #40 Anemometers and two (2) NRG #200P Wind Vanes, as follows:

Anemometers

50 meters facing West

49 meters facing South

40 meters facing West

30 meters facing South

Wind Vanes

50 meters facing North

40 meters facing North

There was also a temperature sensor at a height of 3 meters.

All sensors fed into an NRG Symphonie data logger. The data logger generated wind report files for each day. Data files were sent into the Governor's Energy Office and then to the University of North Dakota for analysis. For this data, UND applied an offset of +322° to the wind vane data. However, the wind vane at 40m appears to have never worked properly and the wind vane at 50m appears to have failed on about July 14, though the data for much of 2006 appears suspect. Thus, some of the wind data should be viewed skeptically. A zipped file that contains all of the NRG raw data files, and the the corrected data and wind resource summary report from UND are available here:

CSU was chosen as the contractor for the program on September 14, 2007. From this data, an analysis of the wind resource report was developed using Windographer 1.21. From anecdotal evidence provided by Mr. Tim Olsen, the wind data appears to be wrongly offset by 180°. Thus, for this data, an offset of +322° - 180° = 142° was applied to the 50m wind vane data and the bad wind vane data from July 14, 2006 through 11/17/2006 was removed. No data quality analysis was performed on this data. The Windographer file and the exported text file from Windographer are given below:

Highlights of the wind resource at this site for the entire data collection period are shown below::

Data Properties

Data Set Starts:

8/18/2005 16:50

Data Set Ends:

11/17/2006 12:50

Data Set Duration:

15 months

Length of Time Step:

10 minutes

Elevation (ft.):

6,499

Calm threshold (mph):

0

Wind Power Coefficients

Power Density at 50m:

490 W/m²

Wind Power Class:

4 (Good)

Wind Shear Coefficients

Power Law Exponent:

0.0362

Surface Roughness:

0.000 m

Roughness Class:

0.00

Roughness Description:

Smooth

Variable

Height above ground (ft)

164 ft (50m)

164 ft (50m)

131 ft (40m)

98 ft (30m)

Mean wind speed (mph)

16.91

17.74

15.93

16.9

Median wind speed (mph)

15.1

16.1

14.2

15.2

Min wind speed (mph)

0.8

0.8

0.8

0.8

Max wind speed (mph)

69.6

71.8

67.5

69.1

Mean power density (W/m²)

482

534

432

467

Mean energy content (kWh/m²/yr)

4,221

4,680

3,783

4,091

Energy pattern factor

2.32

2.24

2.49

2.26

Weibull k

1.66

1.72

1.51

1.70

Weibull c (mph)

18.90

19.88

17.60

18.90

1-hr autocorrelation coefficient

0.82

0.82

0.83

0.82

Diurnal pattern strength

0.03

0.03

0.04

0.05

Hour of peak wind speed

10

11

12

13

Mean turbulence intensity

0.16

0.16

0.17

0.16

Standard deviation (mph)

10.36

10.57

10.37

10.15

Coefficient of variation (%)

61.3

59.6

65.1

60.0

Frequency of calms (%)

0

0

0

0

Actual observations

65,640

65,640

65,640

65,640

Note that this wind rose is only for the 50m wind vane and includes only the data from 2005.

Windographer was used to match up the wind at this site with the performance curves of some common turbines of various sizes and various heights, allowing for losses of about 13%. The table below shows the results. For the larger turbines, the tower height was increased to account for the larger turbine blades - the wind resource was extrapolated to these higher heights. Keep in mind that the larger and the higher the turbine, the better the wind and the greater the output. But of course, as the tower heights and turbine sizes increase so does the cost.